Risk Assessment Of Collapse Disaster Along Nan-yan Section Of Provincial Road S219

Nan-Yan Section of S219Province Road located in the middle north of Mentougou District, is a major route of transportation connecting G109and Changping District. In the study area, the main formation lithology is sedimentary rock and igneous rock and rocks are mainly trachyandesites. breccias lava, basalt, limestone and sort of hard rock. And slopes mainly consist of block structure and cataclastic structure. Based on above engineering geological condition and geological disaster investigation, collapse is the main geological disaster in this area. Because of important geographical location, large car flow, collapse often happens, and consider safe of cars and people, it is necessary to investigate collapse disaster and choose the appropriate control measures in the study area.Based on the geological exploration of S219Nanyan road, statistics collapse slopes and rock falling disaster hidden point and combined with experience literature and former statistical data, we can obtain the types of collapse disaster, distribution feature, development law. In this area, rock falling disaster has two major types: falling-type collapse, slip-type collapse and toppling-type collapse. And then we can analysis the genetic mechanism of collapse.According to the above results, the slope stability in collapse was then analyzed, taking the slope of K24+400-K24+540as an example. Methods of engineering geological analogy, finite element method and stereographic projections were used to the slope stability qualitatively, and stability factor of slope was calculated quantitatively with the the limit equilibrium method ansd the strength reduction method, and futher, and the result of stability analysis was given. This is a basic work for further risk assessment.Meanwhile, in order to investigate highway which is influenced by collapse disaster and rock falling hidden point, thesis evaluate collapse hazard. The assessment includes three aspects. First of all, evaluate the possibility of collapse. The result is mainly from stability evaluation of collapse and based on the "geological disaster risk assessment standard". Second, evaluate the risk level of collapse. We obtain the evaluation by using AHP (analytic hierarchy process) method to build index system and determine index weight, and then use fuzzy mathematical to evaluate. Third, according to the results of former two aspects and the evaluation standard, we assess collapse risk.Based on the results of risk assessment, thesis obtains engineering geological division of collapse in the study area, and gives suggestions and control measures about collapse.